When I was in college 35 years ago, there was a major fad of neo-Malthusian doom-mongering, led by the “Limits to Growth” book and movement. A retreat was organized from the college, and some concerned, environmentally conscious professors and students, myself included, went off for a concentrated seminar in which we educated each other about all the models and dire predictions of the coming collapse.

My roomate became especially concerned, and got hold of the “World Dynamics” modelling system and language (“DYNAMO”) and the Club of Rome model and ran it on Drew University’s IBM 1130 computer.

Our 1130 had less processing power than a modern calculator watch and a grand total of 16,234 bytes of memory. It chugged through this simulation of all the Earth’s economy, resource extraction, technological development, and ecological impacts in just a few minutes, and spat out the graphs telling us we were all doomed.

My roomate got an “A” from his concerned professor, graduated, and went on to be a successful business executive.Limits to Growth is a breathtakingly simplistic model of the phenomena it claims to explain. As one modeller of the period writes in a re-assessment of its hubris,

During the past 30 years I have contributed to this oeuvre in various ways, beginning
with a long-range forecast of technical developments concerning energy’s impact on
the global environment [1]. In the early 1970s I also began using MIT’s DYNAMO in
building models embracing energy, environment, population, and economy. One of
those exercises, a long-term look at CO2 emissions from fossil fuel combustion and their
role in future global warming, was published in 1974, when few people were interested
in such a topic [2].
The reception given to The Limits to Growth [3], the most celebrated forecast of
its time, which used DYNAMO to model the entire world, made me very uneasy about
long-range predictions. When taking the model apart, line by line, I was particularly
astonished by the variables labeled Nonrenewable Resources and Pollution. Lumping
together (to cite just a few of scores of possible examples) highly substitutable but
relatively limited resources of liquid crude oil with unsubstitutable but immense deposits
of sedimentary phosphate rocks, or short-lived atmospheric gases with long-lived radio-
active wastes, struck me as extraordinarily meaningless.
Despite the fact that some writings identiﬁed major ﬂaws of The Limits to Growth
right after the book’s publication [4, 5], too many people took seriously this grotesque
portrayal of the world that pretended to capture the intricate interactions of population,
economy, natural resources industrial production, and environmental pollution with
less than 150 lines of simple equations using dubious assumptions to tie together sweeping
categories of meaningless variables.

A real-world analysis of a controversial prediction made 30 years ago concludes that economic growth cannot be sustained and we are on track for serious economic collapse this century.

The reality behind these rumors is this report by Graham Turner of CSIRO Sustainable Ecosystems. Turner compared real-world statistics to the LtG projections since the 70s and finds that they match, which he claims is evidence that the models must be right.

What did he actually find? In the following, the observed data, running from about 1970 to 2000, is the purple lines with the filled circles. The model we are interested in — the one that it’s claimed the data support — is the green one with open diamonds. (The blue open boxes line is the virtuous “sustainable” world with a per-capita industrial consumption of — I kid you not — $350 per year. (see page 7 here and footnote)) All the y-axes are normalized to arbitrary units in the paper.

Here’s the graph for population:
Sure enough, population went up along the growth track that’s a simple extrapolation from previous growth rates. It fits the LtG model because the LtG model matches a simple exponential growth rate to present date. More to the point, it matches the standard mainstream demographic projections:
– which are based on assumptions of steady economic growth throught the century.
There’s no indication whatsoever that it’s about to peak as LtG predicts. Turner’s paper gives no hint of what he considers to be a null hypothesis, or what he would consider to be a falsifying mismatch of the data to LtG predictions.

Here’s the graph for “services per capita” — the upper purple curve is electricity, the bottom ones are literacy (!):
This parameter shows again just how lousy LtG is as a model of any kind of causality. Literacy rates are strongly affected by worldwide religions which prohibit the education of women; electricity rates, and thus usage, are affected by everything from resource depletion, which they are trying to measure, to political distortion of technology substitution.
Even so, the real-world graphs are just as consistent with a slow-growth or leveling-off null hypothesis as they are with LtG. No hint of a collapse is to be found.

Here’s food per capita:
You would expect food per capita to level off rather than to increase exponentially — once gastronomic satiety is achieved, additional wealth is spent on other pursuits. The actual data fit this null hypothesis perfectly, with no evidence whatsoever than a catastrophic drop is eminent.

Next is industrial output per capita:
Again, perfectly consistent with a standard growth curve with no reason to believe that the LtG has anything to do with reality. Note that the recent dip in output has nothing to do with resource depletion, and everything to do hubristic modellers messing with things they didn’t understand.

Here are non-renewable resources, particularly fossil fuels, shown with upper and lower bounds:
The key to understanding this graph, and indeed the entire LtG mindset, is that they assume there is a fixed amount of something we can’t do without, and then predict that if we continue to consume it, we must necessarily run out. Note, by the way, that even the “sustainable” prediction runs out too, as it must. It just takes longer.
Perhaps one of the reasons that LtG got such play in the 1970s was that they were actually experiencing what was effectively “peak oil”, as I argue here. But the history since then actually bolsters the substitutability argument more than it does a finite-resources point of view.

Second, in the case of energy, other ways of getting the same effect are found, such as buying insulation instead of more heating oil. One of the worst effects of apocalypticism is that it often impedes these efforts and thus becomes a self-fulfilling prophecy. A classic example is the strangulation of nuclear power in the US contemporaneous with LtG. All our currently-running reactors are designs from the 1970s. Compare today’s computers with 1970s ones and see how different the reactors might be today if the same kind of development had taken place.

And finally we have the graph for pollution:
This graph is a case of a complete bait-and-switch. The “actual data” line has nothing to do with anything that was considered pollution in 1972; it’s CO2. CO2 is a very cheesy proxy for pollution, since the Earth has a hormesis response to its levels: too little of it would be as disastrous as too much (ice ages). Meanwhile, the levels of actual pollutants have gone down in the more advanced industral societies even as they have gone up in the more recently-developing ones such as China. History indicates that pollution levels rise with industrialization to a certain level and then decline, a phenomenon that LtG completely ignores. (and if we’re substituting, why can’t we have “computing cycles per capita” in Services?) So I would claim that this graph is comparing apples and oranges and says nothing substantive.

The book predicted that the 21st century would see mass starvation and economic collapse, as humanity exhausted natural resources. … But [Turner's] study in 2008 showed that the book’s predictions of changes in industrial production, food production and pollution had been largely correct[.]

But this is idiotic. All Turner’s figures show is that we’ve been on a nice, steady exponential growth curve. They say nothing whatsoever about “mass starvation and economic collapse.” The paper makes not even the slightest attempt to distinguish cases which would support a simple null hypothesis of continued growth from those which would support LtG. There is not one shred of evidence — none — to support the latter.

23 Responses to “Acolytes of neo-Malthusian Apocalypticism”

“All Turner’s figures show is that we’ve been on a nice, steady exponential growth curve.”

Well I’m sure you know the story of the inventor of the game of chess requesting as his reward the placing of a single grain of rice on the first square of the board then doubling the quantities for each of the following squares. Obviously the King at first thought, no problem, this man is a fool but the joke ended up being on him.

It’s seems that you are either ignorant of the laws of basic physics and the laws that govern complex synergistic interactions of ecosystems or being deliberately disingenuous. These laws are the foundation of the real economy.

As for basing your expectations of the future on past experience I would like to summarize a graph about the life of a turkey over time, from Nassim Taleb’s book “Black Swan”

Basically the turkey is fed by the farmer at a certain time every day over x amount of days. The turkey comes to expect the food and voluntarily comes to the farmers hand even on the day before Thanksgiving when it has no reason to suspect based on historical precedence that this day will be any different. C’est La Vie!

Honestly, a calculator will do nicely for most of these “doomsday” predictions. You don’t need anything more complex. We have x amount of oil, water in circulation and other resources which we are consuming destructively (i.e. in a non renewable fashion) at a certain rate. Absent of about a dozen new, revolutionary inventions to create more energy positive oil, natural gas and biofuels, and are able to regenerate aquifer water, soil, biodiversity without some rather remarkable and draconian limits on their use, we hit limits.

I’d love to believe that new technology will be invented and implemented in time to avert significant resource crises. It’s just not looking that way.

Where does peak-oil fit in those graphs? We’ve just peaked, so good luck with the sentence: “…LtG has anything to do with reality.”
Are you an economist or an engineer? I believe you’re an economist, no sweat, you lack the brains.

All one has to do is chart a yeast population in a batch of beer. We are dependent on many resources that are approaching production peaks, so while our chart is not as simple as yeast, it has many, many single points of failure.

“Something will happen to save us” is a religious theme, not a rationale one.

But the history since then actually bolsters the substitutability argument more than it does a finite-resources point of view.

What’s the cheap replacement for cheap oil? Don’t you realize that spikes in oil prices have preceded the last 4 recessions? Pure coincidence? Roll up the shirt sleeves and put on another cup of coffee, and give it the old college try.

Perhaps an update to the methods would be more appropriate then criticizing 30 year old predicitions made with old modelling techniques and technology. While I support the view point that these predictions cannot be a guide for a world that has changed so drastically as ours has, I disagree with the idea of abandoning the view point that the predictions were created to support based on inaccuracy in said predictions.

Obviously the author has no concept of an exponential function, nor of the laws of thermodynamics. Yes, computing power was very limited in the early 70′s compared to today. There is a quote “all models are wrong, some are useful”. The LTG model has been very useful. The very fact that some people spend so much energy being non-constructively critical of it would attest to its relevance. Does the LTG model have flaws – absolutely. The proper response, however, would be to build a better model, and respect the eye-opening groundwork done on the LTG model.

You who claim there is a finite amount of land and resources are not thinking rationally or critically. The only response post that had any seriousness to it was the man who said fusion power using salt water will or can be used to deal with this problem. Salt water powered fusion and nanoassembler machinery will put an end once and for all to this limits of growth nonsense. The limits to growth people are global socialist one worlders who want to control the world through their globalism. Engines of Creation makes it very clear as does basic science: There is an entire universe of raw materials, energy, and living space out there, and this is not centuries away but mere decades at most.

LtG wasn’t predicting anything. Let me say that again. “Limits to Growth” was not a forecast. It was an attempt to provoke reasoned debate about planned responses to foreseeable problems by describing highly simplified scenarios. Using simplified scenarios is a well-accepted methodology in policy and strategy studies. The book is entirely open about its assumptions and invites people to scrutinise them and modify them, and to assess the issues raised. It pointed out that relatively cheap actions, taken early enough, could circumvent the problems, and invited debate about that. Instead of which, we got 37 years of mischaracterisation and demonisation.

What is it about LtG that is so threatening? Its basic premises are 1) that the quantity of physical matter we can use is finite, 2) that growth tends to be exponential unless checked by some restraint., and 3) harvesting a renewable resource at a rate greater than it is replenished means that it will eventually run out.

Let’s look at these. Premise 1 seems to be the one that everyone chokes on.. But think about it. A simple calculation (first done publicly by Isaac Asimov, as far as I know) shows you that if population grows just one percent per year without constraint, all the matter in the known universe will be in human bodies before 11,000 AD. So there is a limit to the resources available to us. Your “null hypothesis” of continued exponential growth is rejected. If you accept that, it’s just a matter of finding better approximations to the least upper bound.

Premise 2, that growth is exponential unless checked, is more or less universally accepted. There is a large literature on the various checks, and the nature of responses of populations to them. This was controversial at first, but it is now generally accepted and forms the basis of successful management of renewable resources.

Many people attempt to counter premise 3, that overdrawing a stock exhausts it, with substitutability arguments. But substitution cannot be carried out forever – see premise 1. This is why susbstitution was ignored in the model – it adds complexity without providing insight. Remember, LtG was not a forecast, but a set of simplified scenarios..

So, instead of huffing and puffing and beating straw men, how about having a sceptical (in the sense of “seeking the truth”) look at LtG?

“Compare today’s computers with 1970s ones and see how different the reactors might be today if the same kind of development had taken place.”

Yeah, right. This is the old “if cars had developed like computers, they would go 1000 mph and get 2,000 miles per gallon” argument. To which the response is “yes – and they would seat 100 people and be the size of a matchbox.”

The analogy is misleading, at best. It would be better to compare nuclear reactors to passenger jets.

People still going on about ‘Peak Oil?’ We have enough coal for centuries, and coal can be turned into oil at $50 a barrel, South Africa did this during the embargo, it’s not economical for this to be done on a large scale though because Oil does not reliably stay about $50 a barrel, and if they build a bunch of coal-to-oil plants and the price of oil falls, they will go out of business and lose billions. Once oil is reliably above $50 a barrel we will see coal-to-oil on a large scale.

And calling nanotech religious is just plain ignorant, so I won’t comment further. But nanotech and AI will eliminate these problems, if people are so concerned about peak this and running out of that, they would be wise to, I dunno, spend a little money on nanotech/AI. Nanotech and AI get a few million dollars in research dollars every year, how many billions do we spend investigating environmental issues and worrying about polar bears, when nanotech/AI is the only sure fix?

Everything runs out or runs down. One doesn’t need a computer model for that. It is how humans respond to that truism that determines who lives and who dies. Hint: Politicians, journos, and academics don’t have what it takes to respond constructively to real world problems. If you listen to them, you die.

Find real world problem solvers and learn synergistic problem solving. If you have to secede from the loser mass majority eventually, be prepared to do so. Most people would rather whine than solve problems. Monkey brains in human bodies. If you want to live, never leave my side … Heh! Actually if you want to live, learn to solve problems so you don’t end up eating dead bodies as in Cormac McCarthy’s “The Road.”

We are not going to run out of metals. About 80% of those ever mined are still in use and will be recycled in ever more efficient manners.

BTW I think the Polywell Fusion Reactor is a very good near term prospect for fusion. If they do produce energy as cheaply as predicted they can be used in tertiary oil field recovery. That alone increases current oil resources by 30% or so with no change in prices.